Are you using gnome-shell and having multiple users logging in during the day? Or otherwise having many VT changes? The system is quite stable when I am the only one using it. Having other users logging in seems to cause trouble. Having firefox open may have some effect.

Anyways, I even went so far and created a new account to myself and I am copying all my data to that users directories so I can rule out any configuration setting in my personal config files.